In the mid- to late summer of 1860, billions of soft pink and white Gossypium hirsutum blooms broke out across South Carolina, Georgia, western Tennessee, Mississippi, Alabama, Arkansas, Louisiana, and Texas, soon to morph into puffy white bolls. Nearly 3 million black slaves fanned across this flowery inland sea. By season’s end in early winter, their harvest totaled the largest on record: with the seeds ginned out, a crop of 4 million 500-pound bales.

Ever since sometime in the early 17th century when a European colonist first pushed a cotton seed into the New World earth, the South’s rich soil and hot, humid climate had rewarded planters. But large-scale production did not develop until the early to mid-19th century, when several factors fell into place. Eli Whitney’s 1793 cotton gin had enabled the efficient, mechanized cleaning of cotton. The Industrial Revolution in England had enabled the mass production of such items as cotton garments, creating an immense demand for the commodity. And, crucially, the existing agricultural labor force of African American slaves had swelled from 700,000 in 1790 to 4 million in 1860. Cotton soon became know as “white gold,” although a more apt comparison for today would be with crude oil. Cotton, just as oil, could buy arms, finance war, and lay the economic foundation of a nation.

That bumper crop just a century and a half ago would dramatically bolster the South’s confidence in its international economic power and help give the newly formed Confederate States of America the backbone to initiate a bold war for independence in April 1861 against an opponent with far greater and more diverse resources. The American Civil War truly began in the Southern cotton fields during the previous summer.

It’s not hard to see how King Cotton catapulted the South into a world-trade superpower. In 1860 the value ofAmerican exports totaled $333 million, cotton contributing $191 million or 58 percent. By contrast, other slave-produced exports—tobacco (6 percent) and rice (1 percent)—were insignificant. In 1846 the young Karl Marx had noted that “Without cotton you have no modern industry . . . without slavery, you have no cotton.” The linkage was indisputable: more than 70 percent of American slaves were involved with cotton production. The price of a slave was directly related to that of cotton. Slavery spread only to areas where cotton could grow.

Cotton’s extraordinary economic power had perhaps been most famously expressed in the U.S. Senate on March 4, 1858: “You dare not to make war on cotton,” warned South Carolina’s James Henry Hammond. “No power on earth dares make war upon it. Cotton is King.” The passionate senator went on to declare that “the wealth of a nation like that of a man is to be estimated by its surplus production.” That meant exports. Hammond boldly advanced the notion of an independent nation, a “South organized separately” upon its cotton revenues. Without Southern slave-produced cotton, “England,” said Hammond, “would topple headlong and carry the whole civilized world with her save the South.” Southern nationhood and world order alike might rest upon the shoots of this unassuming shrub.

The bellicose South Carolinian was neither the first nor the last to threaten opponents with the “irresistible power” of cotton. “Cotton bags [bales],”a partner of financier Nicholas Biddle of Philadelphia had boasted in 1839, “will be much more effectual in bringing John Bull [England] to terms than all the disciplined troops America could bring into the field.” Biddle was scheming to withhold cotton from England for profit in the marketplace, not military victory; but he bet wrong and his firm came crashing down.

Great Britain had built a great industry out of turning cotton yarn and thread into breathable, soft, comfortable garments. Dozens of textile mill towns spread across Lancashire and the northwestern English countryside. The United States became England’s most significant supplier because it could provide significant volume and a clean product. American ingenuity also helped with creative financing, relatively cheap shipping, and the development of new and more usable cotton strains. Above all, the American South availed itself of its massive enslaved labor force. By 1860 Britain imported more than 80 percent of its cotton from the South; more than half of 1860’s yield went there.

The anything-but-radical Blackwood’s Magazine had fretted over the “power of an oligarchy of [cotton] planters” in 1853, not a vague concern when fully one-fifth of Britain’s 22 million people were tied directly or indirectly to the textile industry. A serious shortage of cotton might rip the social fabric by throwing millions out of work and potentially lead to social revolution. Economic blackmail could be used to force England into the War for Southern Independence as a powerful ally of the Confederacy, or at least to encourage the British to advocate for the North’s recognition of Southern independence.

In his inaugural address on February 18, 1861, Jefferson Davis, the newly elected president of the Confederacy, wasted little time in leveraging King Cotton. He cautioned Britain and the North that to obstruct cotton’s “transmission to foreign markets . . . would be detrimental to manufacturing and commercial interests abroad.” Then, when the U.S. government responded with force, Davis initiated an embargo of cotton with the nearly unanimous approval of his people.

Born of states’ rights, the Confederacy left enforcement of the embargo and the restriction of production to its component states. Louisiana forbade cotton to be brought into New Orleans after October 10, 1861, and burnt what had arrived rather than try to ship it out; patriotic Confederates rejoiced at the sight of great fires roaring in their ports. South Carolinian Edmund Rhett told the London Times that “you British must recognize us before the end of October [1861] because of cotton requirements.”

Abraham Lincoln understood how the South was playing its cards and, not to be outdone by the Confederate embargo, imposed a Union blockade, an odd juxtaposition of policies by adversaries, both designed to prevent cotton from leaving the South. Prices spiraled from 10 cents to nearly two dollars a pound. Smuggling flourished.

Ironically, the Confederacy’s King Cotton strategy would fail because the arrogance-feeding harvests of the late 1850s and 1860 had given English textile factories great stockpiles on the eve of the war. The blockade- and embargo-fostered cotton famine would not begin to bite until 1862, when it was too late. The South had gambled disastrously, inexplicably not factoring in the surplus British inventories.

In September 1862, just as the mills finally began to grind down, the Union’s Army of the Potomac sent the Confed-erate Army of Northern Virginia reeling back out of Maryland. The rising ascendancy of the Union and the British fear of a Union invasion of Canada would now dictate Britain’s response to the Civil War.

By the end of 1862, Britain began feeling the pinch of the embargo, and a half million Lancashire residents went on the dole. By 1864 the “total destitute population” had risen to 811,000. Eager to win new friends, New York and Philadelphia businessmen sent the George Griswold and the Achilles to Liverpool, laden with flour, meat, and rice for the workers.

Despite its flawed strategy of embargo, the South used cotton effectively to barter for a large amount of British armaments. The CSS Fingal slipped through the blockade to land “15,000 Enfield rifles, more than two million cartridges . . . seven tons of artillery shells” at Savannah on November 12, 1861. Railcars took the payload in April to supply Albert Sidney Johnston’s men at the bloody Shiloh offensive in southwestern Tennessee. Three English-built raiders—the Alabama, Florida, and Shenandoah—ravaged the Union’s merchant marine. In 1872 Britain would pay reparations to the United States for these raiders’ depredations.

In March 1863 the cosmopolitan Confederate Secretary of State Judah P. Benjamin introduced the sophisticated Erlanger cotton bond for the European market, a precursor of modern international securities. Their interest and principal payable in either French francs or British sterling, the bonds were traded on several European exchanges. Their true enticement rested upon their convertibility into cotton, a viable substitute for gold. But Benjamin’s inspiration came too late to alter the outcome of the war.

Six weeks before Lee surrendered at Appomattox Court House, a writer in the New York Times called for a restoration of cotton production led by “white ingenuity and enterprise” combined with “black labor.” Not long after, the South’s “God-made monopoly” had regained three-quarters of the world’s export market. From the Civil War until the 1930s, cotton would remain America’s leading export.